Chair seat and backrest



FIG. 1 is a front perspective view of a chair seat and backrest according to our new design;

FIG. 2 is a back perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a back view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof; and,

FIG. 7 is a top view thereof.

Features shown in dashed lines form no part of the claimed design. 

The ornamental design of a chair seat and backrest, as shown and described. 